JP 2005-64515A (Patent Document 1) discloses an example of a substrate storage condition inspecting apparatus as described above. According to the configuration of Patent Document 1, an imaging device captures an image of a semiconductor substrate stored in a transport container, the angle of inclination of the semiconductor substrate relative to the horizontal direction is calculated on the basis of the captured image, and it is determined whether or not an abnormal storage condition has occurred in which, for example, the semiconductor substrate is stored in a laterally inclined orientation.
The substrate storage condition inspecting apparatus of Patent Document 1 needs to perform, for all of a plurality of semiconductor substrates, a complex analysis that involves extracting, from the captured image of each semiconductor substrate, edges of a plurality of locations of the semiconductor substrate that are circumferentially aligned in the peripheral edge portion, determining a straight line connecting the plurality of edges for each semiconductor substrate, and determining the inclination of the semiconductor substrate from the angle of inclination of the straight line relative to the horizontal direction. This has complicated the configuration for determining whether or not a semiconductor substrate is in an abnormal storage condition inside the transport container.